Flow cytometry requires optical sources to be focused on a small stream of fluid for the purpose of illuminating particles, which may be cells, chromosomes, viruses, etc. in the stream of fluid. The particles are then sorted based upon the emissions of fluorochromes that have been used to dye or stain the particles. The processes of illuminating the particles and subsequently sorting these particles are very complex. Optical focusing systems to focus multiple laser beams, as well as optical imaging systems to collect the responses of the particles to the laser excitation, must be deployed in a confined area. As such, the optical systems employed by flow cytometers must be compact and provide a high degree of functionality.